National Pollutant Discharge Elimination System (NPDES)

Status of Nutrient Requirements for NPDES-Permitted Facilities

Discharges from municipal wastewater treatment facilities with little to no treatment for nitrogen and phosphorus are a significant source of these nutrients to surface waters throughout the country. Setting permit limits and treating the wastewater to meet specific effluent limits can substantially reduce nitrogen and phosphorus loading from these facilities, protecting local and downstream water quality as a result. The data in this indicator represent major (≥1 million gallons/day (MGD)) and non-major ("minor," <1 MGD) municipal wastewater treatment facilities with individual National Pollutant Discharge Elimination System (NPDES) permits.

Presented by state or territory of the U.S. are the counts and percentages of such facilities that have permit limits1 or monitoring requirements only, for any nutrient pollution parameter. Please refer to the data protocol document, "Nutrient Data Compilation and Analysis Outline," for details on how the data were generated and produced.

The data tables are based on February 2016 data from EPA's Integrated Compliance Information System (ICIS) database.

This table presents the total number of individual permitted WWTFs that have nitrogen limits only, phosphorus limits only, or have limits for both pollutants. These data include all individual, non-stormwater NPDES permitted facilities with data in ICIS as of February 2016. (The data include EPA-issued permits and tribal permits. The data only include limits with measuring units that are either mass-based or concentration-based. WWTFs are publicly-owned treatment works (POTWs) with the primary permit standard industrial classification ("SIC") code 4952, and where there is no SIC code, the Facility Type Indicator field is labled "POTW.")

EPA Region

State

Universe of
Majors

Nitrogen Only
(Number)

Nitrogen Only
(Percent)

Phosphorus Only
(Number)

Phosphorus Only
(Percent)

Both
N and P
(Number)

Both
N and P
(Percent)

Any
(N or P or Both)
(Number)

Any
(N or P or Both)
(Percent)

10

AK

20

0

0

0

0

0

0

0

0

4

AL

119

19

16

3

3

14

12

36

30

6

AR

78

2

3

9

12

7

9

18

23

9

AS(4)

2

0

0

0

0

0

0

0

0

9

AZ

48

2

4

1

2

3

6

6

13

9

CA

175

68

39

0

0

7

4

75

43

8

CO

91

12

13

6

7

5

5

23

25

1

CT(2)

64

1

2

13

20

0

0

14

22

3

DC

2

0

0

1

50

0

0

1

50

3

DE

8

0

0

0

0

5

63

5

63

4

FL(5)

94

13

14

1

1

51

54

65

69

4

GA

151

0

0

74

49

0

0

74

49

6

GM

0

0

0

0

0

0

0

0

0

9

GU

3

0

0

0

0

0

0

0

0

9

HI

2

1

50

0

0

0

0

1

50

7

IA(3),(6)

96

13

14

1

1

0

0

14

15

10

ID

28

0

0

14

50

1

4

15

54

5

IL

214

0

0

58

27

0

0

58

27

5

IN

133

0

0

58

44

0

0

58

44

7

KS

45

0

0

0

0

0

0

0

0

4

KY

87

0

0

22

25

0

0

22

25

6

LA

105

0

0

0

0

0

0

0

0

1

MA

91

1

1

45

49

8

9

54

59

3

MD

47

1

2

1

2

41

87

43

91

1

ME

61

0

0

5

8

0

0

5

8

5

MI

105

0

0

105

100

0

0

105

100

5

MN

75

0

0

50

67

0

0

50

67

7

MO

123

1

1

8

7

0

0

9

7

9

MP(4)

2

0

0

0

0

2

100

2

100

4

MS

65

0

0

0

0

16

25

16

25

8

MT

21

2

10

0

0

11

52

13

62

4

NC(2)

147

1

1

23

16

4

3

28

19

8

ND(3)

16

0

0

1

6

0

0

1

6

7

NE

30

1

3

0

0

0

0

1

3

1

NH

36

2

6

14

39

0

0

16

44

2

NJ(3),(7)

92

0

0

28

30

7

8

35

38

6

NM

22

2

9

1

5

1

5

4

18

9

NV

7

1

14

1

14

1

14

3

43

2

NY

211

30

14

64

30

5

2

99

47

5

OH

205

0

0

101

49

5

2

106

52

6

OK

69

3

4

2

3

0

0

5

7

10

OR

50

0

0

4

8

0

0

4

8

3

PA

291

0

0

35

12

109

37

144

49

2

PR(4)

33

13

39

1

3

16

48

30

91

1

RI

19

6

32

1

5

5

26

12

63

4

SC

98

0

0

16

16

0

0

16

16

8

SD

20

0

0

0

0

0

0

0

0

4

TN

107

2

2

1

1

15

14

18

17

6

TX(8)

489

3

1

29

6

1

0

33

7

8

UT

29

0

0

2

7

0

0

2

7

3

VA(2)

92

10

11

4

4

40

43

54

59

2

VI(4)

2

0

0

0

0

0

0

0

0

1

VT(3)

0

0

0

0

0

0

0

0

0

10

WA(3)

48

1

2

2

4

0

0

3

6

5

WI

86

0

0

86

100

0

0

86

100

3

WV

50

3

6

2

4

6

12

11

22

8

WY(3)

16

0

0

0

0

0

0

0

0

Total

4,420

214

5

893

20

386

9

1,493

34

Notes:
(1) Note that all permits with limits should also have corresponding monitoring requirements for each parameter that is limited to track compliance.
(2) These states have watershed-based permitting for multiple dischargers for nutrients. These permits/facilities may not be reflected in this table. (VA - approximately 112 WWTFs covered for N & P; NC - approximately 54 WWTF covered for N; and CT - approximately 79 facilities covered for N)
(3) IA, ND, VT, WA, and WY did not have primary SIC codes entered into the Permit Basic Info section of ICIS for most or all of their facilities. NJ has only entered SIC codes for 46 percent of its individual permittees in ICIS.
(4) The following territories and regions are included in these tables: American Samoa (AS), Gulf of Mexico (GM), Guam (GU), Northern Mariana Islands (MP), Puerto Rico (PR), and U.S. Virgin Islands (VI).
(5) Upon review, this state indicated that it uses other monitoring location codes in addition to the ones used for this analysis. [FL]
(6) Iowa is in the process of transitioning to a new NPDES database and is working to ensuring accurate transfer and migration of required data into the EPA ICIS-NPDES data system. This process is expected to be complete by summer 2017.
(7) This state noted that its data are batch-loaded into ICIS, and therefore there are some errors based on the state's records. [NJ]
(8) This state indicated that the data managed to capture 12 permits that are either for stormwater (MS4) or industrial facilities. [TX]

Note that at the time of this data collection from ICIS-NPDES, data for non-major facilities were not required to be entered into the system. Therefore, the data below represent what was in the system at the time of the collection, and may not reflect the entire universe of facilities as well as limit and monitoring requirements.

EPA Region

State

Universe of Non-majors

Nitrogen Only
(Number)

Nitrogen Only
(Percent)

Phosphorus Only
(Number)

Phosphorus Only
(Percent)

Both
N and P
(Number)

Both
N and P
(Percent)

Any
(N or P or Both)
(Number)

Any
(N or P or Both)
(Percent)

10

AK

7

0

0

0

0

0

0

0

0

4

AL

259

26

10

11

4

8

3

45

17

6

AR

311

4

1

13

4

3

1

20

6

9

AS(4)

0

0

0

0

0

0

0

0

0

9

AZ

57

4

7

0

0

4

7

8

14

9

CA

85

14

16

0

0

1

1

15

18

8

CO

156

9

6

11

7

2

1

22

14

1

CT(2)

23

4

17

10

43

0

0

14

61

3

DC

0

0

0

0

0

0

0

0

0

3

DE

7

0

0

1

14

3

43

4

57

4

FL(5)

80

12

15

2

3

33

41

47

59

4

GA

192

0

0

31

16

1

1

32

17

6

GM(4)

0

0

0

0

0

0

0

0

0

9

GU(4)

3

0

0

0

0

2

67

2

67

9

HI

0

0

0

0

0

0

0

0

0

7

IA(3),(6)

703

114

16

1

0

0

0

115

16

10

ID

90

2

2

20

22

2

2

24

27

5

IL

398

1

0

25

6

1

0

27

7

5

IN

369

0

0

65

18

0

0

65

18

7

KS

418

1

0

0

0

1

0

2

0

4

KY

182

0

0

26

14

0

0

26

14

6

LA

364

1

0

0

0

1

0

2

1

1

MA

29

1

3

12

41

0

0

13

45

3

MD

127

6

5

7

6

37

29

50

39

1

ME

71

1

1

0

0

0

0

1

1

5

MI

162

0

0

130

80

0

0

130

80

5

MN

287

0

0

5

2

0

0

5

2

7

MO

1,316

2

0

52

4

1

0

55

4

9

MP(4)

1

0

0

0

0

0

0

0

0

4

MS

292

0

0

1

0

16

5

17

6

8

MT

86

7

8

0

0

18

21

25

29

4

NC(2)

264

0

0

21

8

1

0

22

8

8

ND(3)

29

0

0

0

0

0

0

0

0

7

NE

266

7

3

0

0

0

0

7

3

1

NH

13

0

0

8

62

0

0

8

62

2

NJ(3),(7)

141

0

0

33

23

5

4

38

27

6

NM

37

1

3

1

3

4

11

6

16

9

NV

7

2

29

0

0

3

43

5

71

2

NY

388

16

4

73

19

1

0

90

23

5

OH

1,083

2

0

113

10

5

0

120

11

6

OK

201

0

0

6

3

0

0

6

3

10

OR

132

0

0

0

0

0

0

0

0

3

PA

672

0

0

2

0

75

11

77

11

2

PR(4)

17

1

6

2

12

14

82

17

100

1

RI

0

0

0

0

0

0

0

0

0

4

SC

66

0

0

1

2

0

0

1

2

8

SD

171

1

1

0

0

1

1

2

1

4

TN

299

3

1

3

1

16

5

22

7

6

TX(8)

1,323

2

0

32

2

3

0

37

3

8

UT

32

0

0

2

6

0

0

2

6

3

VA(2)

255

0

0

0

0

1

0

1

0

2

VI(4)

12

0

0

5

42

0

0

5

42

1

VT(3)

1

0

0

0

0

0

0

0

0

10

WA(3)

193

1

1

0

0

2

1

3

2

5

WI

467

0

0

8

2

0

0

8

2

3

WV

239

38

16

1

0

16

7

55

23

8

WY(3)

57

0

0

0

0

0

0

0

0

Total

12,440

283

2

734

6

281

2

1,298

10

Notes:
(1) Note that all permits with limits should also have corresponding monitoring requirements for each parameter that is limited to track compliance.
(2) These states have watershed-based permitting for multiple dischargers for nutrients. These permits/facilities may not be reflected in this table. (VA - approximately 112 WWTFs covered for N & P; NC - approximately 54 WWTF covered for N; and CT - approximately 79 facilities covered for N)
(3) IA, ND, VT, WA, and WY did not have primary SIC codes entered into the Permit Basic Info section of ICIS for most or all of their facilities. NJ has only entered SIC codes for 46 percent of its individual permittees in ICIS.
(4) The following territories and regions are included in these tables: American Samoa (AS), Gulf of Mexico (GM), Guam (GU), Northern Mariana Islands (MP), Puerto Rico (PR), and U.S. Virgin Islands (VI).
(5) Upon review, this state indicated that it uses other monitoring location codes in addition to the ones used for this analysis. [FL]
(6) Iowa is in the process of transitioning to a new NPDES database and is working to ensuring accurate transfer and migration of required data into the EPA ICIS-NPDES data system. This process is expected to be complete by summer 2017.
(7) This state noted that its data are batch-loaded into ICIS, and therefore there are some errors based on the state's records. [NJ]
(8) This state indicated that the data managed to capture 12 permits that are either for stormwater (MS4) or industrial facilities. [TX]

Table 3. Number and Percent of Major Municipal Sewage Treatment Facilities with Nitrogen (N) and/or Phosphorus (P) Monitoring Requirements for Monitoring Only Purposes or for Compliance with an Effluent Limit

This table represents the total number of individual permitted WWTFs that have monitoring requirements for nitrogen only, phosphorus only, or have monitoring requirements for both pollutants. These data include all individual, non-stormwater NPDES permitted facilities with data in ICIS as of February 2016. (These data include EPA-issued permits and tribal permits. These data only include requirements with measuring units that are either mass-based or concentration-based. WWTFs are publicly-owned treatment works (POTWs) with the primary permit standard industrial classification ("SIC") code 4952, and where there is no SIC code, the Facility Type Indicator field is labled "POTW.")

EPA Region

State

Universe of
Majors

Nitrogen Only
(Number)

Nitrogen Only
(Percent)

Phosphorus Only
(Number)

Phosphorus Only
(Percent)

Both
N and P
(Number)

Both
N and P
(Percent)

Any
(N or P or Both)
(Number)

Any
(N or P or Both)
(Percent)

10

AK

20

1

5

0

0

0

0

1

5

4

AL

119

0

0

0

0

119

100

119

100

6

AR

78

6

8

9

12

51

65

66

85

9

AS(4)

2

0

0

0

0

0

0

0

0

9

AZ

48

0

0

0

0

43

90

43

90

9

CA

175

26

15

2

1

116

66

144

82

8

CO

91

26

29

3

3

5

5

34

37

1

CT(2)

64

0

0

42

66

2

3

44

69

3

DC

2

0

0

0

0

2

100

2

100

3

DE

8

1

13

0

0

4

50

5

63

4

FL(5)

94

3

3

8

9

35

37

46

49

4

GA

151

0

0

78

52

43

28

121

80

6

GM(4)

0

0

0

0

0

0

0

0

0

9

GU(4)

3

0

0

0

0

0

0

0

0

9

HI

2

0

0

0

0

2

100

2

100

7

IA(3),(6)

96

2

2

5

5

51

53

58

60

10

ID

28

1

4

3

11

22

79

26

93

5

IL

214

27

13

20

9

149

70

196

92

5

IN

133

1

1

75

56

13

10

89

67

7

KS

45

0

0

0

0

45

100

45

100

4

KY

87

10

11

10

11

66

76

86

99

6

LA

105

0

0

1

1

12

11

13

12

1

MA

91

21

23

18

20

43

47

82

90

3

MD

47

0

0

0

0

47

100

47

100

1

ME

61

0

0

14

23

0

0

14

23

5

MI

105

0

0

20

19

0

0

20

19

5

MN

75

15

20

9

12

50

67

74

99

7

MO

123

3

2

1

1

30

24

34

28

9

MP(4)

2

0

0

0

0

0

0

0

0

4

MS

65

0

0

0

0

61

94

61

94

8

MT

21

1

5

0

0

20

95

21

100

4

NC(2)

147

24

16

0

0

106

72

130

88

8

ND(3)

16

0

0

0

0

8

50

8

50

7

NE

30

0

0

0

0

24

80

24

80

1

NH

36

6

17

15

42

2

6

23

64

2

NJ(3),(7)

92

2

2

17

18

44

48

63

68

6

NM

22

1

5

1

5

1

5

3

14

9

NV

7

1

14

0

0

6

86

7

100

2

NY

211

83

39

8

4

90

43

181

86

5

OH

205

79

39

1

0

120

59

200

98

6

OK

69

2

3

0

0

1

1

3

4

10

OR

50

2

4

0

0

26

52

28

56

3

PA

291

12

4

8

3

196

67

216

74

2

PR(4)

33

5

15

0

0

0

0

5

15

1

RI

19

10

53

0

0

9

47

19

100

4

SC

98

18

18

3

3

56

57

77

79

8

SD

20

6

30

0

0

5

25

11

55

4

TN

107

2

2

0

0

83

78

85

79

6

TX(8)

489

7

1

9

2

6

1

22

4

8

UT

29

0

0

1

3

23

79

24

83

3

VA(2)

92

12

13

3

3

22

24

37

40

2

VI(4)

2

0

0

2

100

0

0

2

100

1

VT(3)

0

0

0

0

0

0

0

0

0

10

WA(3)

48

2

4

1

2

35

73

38

79

5

WI

86

0

0

69

80

17

20

86

100

3

WV

50

0

0

0

0

18

36

18

36

8

WY(3)

16

1

6

1

6

0

0

2

13

Total

4,420

419

9

457

10

1,929

44

2,805

63

Notes:
(1) Note that all permits with limits should also have corresponding monitoring requirements for each parameter that is limited to track compliance.
(2) These states have watershed-based permitting for multiple dischargers for nutrients. These permits/facilities may not be reflected in this table. (VA - approximately 112 WWTFs covered for N & P; NC - approximately 54 WWTF covered for N; and CT - approximately 79 facilities covered for N)
(3) IA, ND, VT, WA, and WY did not have primary SIC codes entered into the Permit Basic Info section of ICIS for most or all of their facilities. NJ has only entered SIC codes for 46 percent of its individual permittees in ICIS.
(4) The following territories and regions are included in these tables: American Samoa (AS), Gulf of Mexico (GM), Guam (GU), Northern Mariana Islands (MP), Puerto Rico (PR), and U.S. Virgin Islands (VI).
(5) Upon review, this state indicated that it uses other monitoring location codes in addition to the ones used for this analysis. [FL]
(6) Iowa is in the process of transitioning to a new NPDES database and is working to ensuring accurate transfer and migration of required data into the EPA ICIS-NPDES data system. This process is expected to be complete by summer 2017.
(7) This state noted that its data are batch-loaded into ICIS, and therefore there are some errors based on the state's records. [NJ]
(8) This state indicated that the data managed to capture 12 permits that are either for stormwater (MS4) or industrial facilities. [TX]

Table 4. Number and Percent of Non-major Municipal Sewage Treatment Facilities with Nitrogen (N) and/or Phosphorus (P) Monitoring Requirements for Monitoring Only Purposes or for Compliance with an Effluent Limit

Note that at the time of this data collection from ICIS-NPDES, data for non-major facilities were not required to be entered into the system. Therefore, the data below represent what was in the system at the time of the collection and may not reflect the entire universe of facilities as well as limit and monitoring requirements.

EPA Region

State

Universe of Non-majors

Nitrogen Only
(Number)

Nitrogen Only
(Percent)

Phosphorus Only
(Number)

Phosphorus Only
(Percent)

Both
N and P
(Number)

Both
N and P
(Percent)

Any
(N or P or Both)
(Number)

Any
(N or P or Both)
(Percent)

10

AK

7

0

0

0

0

1

14

1

14

4

AL

259

0

0

1

0

258

100

259

100

6

AR

311

3

1

7

2

7

2

17

5

9

AS(4)

0

0

0

0

0

0

0

0

0

9

AZ

57

1

2

1

2

42

74

44

77

9

CA

85

5

6

5

6

21

25

31

36

8

CO

156

23

15

11

7

7

4

41

26

1

CT(2)

23

0

0

12

52

3

13

15

65

3

DC

0

0

0

0

0

0

0

0

0

3

DE

7

0

0

0

0

4

57

4

57

4

FL(5)

80

4

5

4

5

34

43

42

53

4

GA

192

5

3

25

13

13

7

43

22

6

GM(4)

0

0

0

0

0

0

0

0

0

9

GU(4)

3

0

0

0

0

0

0

0

0

9

HI

0

0

0

0

0

0

0

0

0

7

IA(3),(6)

703

0

0

2

0

6

1

8

1

10

ID

90

1

1

33

37

22

24

56

62

5

IL

398

14

4

47

12

11

3

72

18

5

IN

369

0

0

28

8

0

0

28

8

7

KS

418

4

1

89

21

111

27

204

49

4

KY

182

19

10

3

2

142

78

164

90

6

LA

364

0

0

0

0

13

4

13

4

1

MA

29

8

28

3

10

9

31

20

69

3

MD

127

1

1

1

1

84

66

86

68

1

ME

71

2

3

2

3

0

0

4

6

5

MI

162

0

0

39

24

0

0

39

24

5

MN

287

1

0

8

3

2

1

11

4

7

MO

1,316

30

2

50

4

92

7

172

13

9

MP(4)

1

0

0

0

0

0

0

0

0

4

MS

292

0

0

0

0

78

27

78

27

8

MT

86

3

3

0

0

66

77

69

80

4

NC(2)

264

12

5

0

0

42

16

54

20

8

ND(3)

29

1

3

0

0

0

0

1

3

7

NE

266

19

7

0

0

156

59

175

66

1

NH

13

0

0

7

54

2

15

9

69

2

NJ(3),(7)

141

3

2

23

16

28

20

54

38

6

NM

37

0

0

1

3

4

11

5

14

9

NV

7

1

14

0

0

3

43

4

57

2

NY

388

62

16

57

15

33

9

152

39

5

OH

1,083

67

6

91

8

426

39

584

54

6

OK

201

0

0

4

2

0

0

4

2

10

OR

132

1

1

0

0

1

1

2

2

3

PA

672

0

0

2

0

77

11

79

12

2

PR(4)

17

0

0

0

0

0

0

0

0

1

RI

0

0

0

0

0

0

0

0

0

4

SC

66

3

5

9

14

21

32

33

50

8

SD

171

6

4

8

5

6

4

20

12

4

TN

299

2

1

7

2

40

13

49

16

6

TX(8)

1,323

3

0

11

1

2

0

16

1

8

UT

32

0

0

0

0

28

88

28

88

3

VA(2)

255

0

0

0

0

1

0

1

0

2

VI(4)

12

0

0

0

0

0

0

0

0

1

VT(3)

1

0

0

0

0

0

0

0

0

10

WA(3)

193

15

8

5

3

96

50

116

60

5

WI

467

1

0

11

2

0

0

12

3

3

WV

239

0

0

0

0

60

25

60

25

8

WY(3)

57

0

0

1

2

13

23

14

25

Total

12,440

320

3

608

5

2,065

17

2,993

24

Notes:
(1) Note that all permits with limits should also have corresponding monitoring requirements for each parameter that is limited to track compliance.
(2) These states have watershed-based permitting for multiple dischargers for nutrients. These permits/facilities may not be reflected in this table. (VA - approximately 112 WWTFs covered for N & P; NC - approximately 54 WWTF covered for N; and CT - approximately 79 facilities covered for N)
(3) IA, ND, VT, WA, and WY did not have primary SIC codes entered into the Permit Basic Info section of ICIS for most or all of their facilities. NJ has only entered SIC codes for 46 percent of its individual permittees in ICIS.
(4) The following territories and regions are included in these tables: American Samoa (AS), Gulf of Mexico (GM), Guam (GU), Northern Mariana Islands (MP), Puerto Rico (PR), and U.S. Virgin Islands (VI).
(5) Upon review, this state indicated that it uses other monitoring location codes in addition to the ones used for this analysis. [FL]
(6) Iowa is in the process of transitioning to a new NPDES database and is working to ensuring accurate transfer and migration of required data into the EPA ICIS-NPDES data system. This process is expected to be complete by summer 2017.
(7) This state noted that its data are batch-loaded into ICIS, and therefore there are some errors based on the state's records. [NJ]
(8) This state indicated that the data managed to capture 12 permits that are either for stormwater (MS4) or industrial facilities. [TX]